Back contact cell, cell assembly and photovoltaic system

Abstract

The invention relates to the technical field of solar cells, and provides a back contact cell, a cell assembly and a photovoltaic system, in the back contact cell, on one hand, due to the arrangement of a first bus line, even if a first fine grid is disconnected at a first edge serial connection area, the first fine grid is not disconnected at the first edge serial connection area; on one hand, current collected by the first edge grid lines can be collected through the first bus lines and transmitted to the welding strips arranged in the adjacent second edge series connection areas, so that efficiency loss is effectively avoided, and on the other hand, due to the fact that the first fine grids are disconnected at the first edge series connection areas, efficiency loss is effectively avoided. The height of the first part of the first bus line is smaller than the height of the second part of the first bus line, and in the assembly, after the first insulating layer is arranged, the height of the first insulating layer can be reduced, so that the cold solder joint risk caused by the first insulating layer is reduced, and the influence of cold solder joint on the back contact battery is reduced.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and more particularly to a back-contact cell, a cell module, and a photovoltaic system. Background Technology

[0002] A back-contact solar cell is a type of solar cell in which both P-type and N-type doped layers are disposed on the back side of a silicon wafer, with no metal electrodes obstructing the front side. It exhibits higher short-circuit current and conversion efficiency. The back side of a back-contact solar cell features alternating positive and negative electrode grids.

[0003] In related technologies, to avoid increasing the risk of microcracks caused by soldering the solder strips at the edge of the back contact battery, busbars are typically placed at the edge of the back contact battery to collect the current in the edge region. Then, by making a portion of the fine grid continuous at adjacent solder strips with opposite polarities, the current in the edge region is collected and fed to the solder strip in the middle. The busbars are only used for current collection and not for soldering, which can reduce the risk of microcracks while ensuring current collection efficiency. However, in this case, since some of the fine grids are uninterrupted at the opposite polarity solder strips, insulating adhesive needs to be placed at the opposite polarity grid lines that intersect with the solder strips to prevent leakage. Because the insulating adhesive is relatively high, it can push up the solder strip during soldering, making it prone to poor soldering on both sides of the insulating adhesive. Summary of the Invention This application provides a back-contact battery, a battery module, and a photovoltaic system.

[0004] This application is implemented as follows: the back contact battery in the embodiments of this application includes: A silicon substrate having opposing front and back sides, the back side having opposing first and second edges in a first direction, the back side including a plurality of first regions and a plurality of second regions alternately arranged along a second direction intersecting the first direction, the back side having a plurality of first interconnection regions and a plurality of second interconnection regions, the first interconnection regions and the second interconnection regions being alternately arranged in the first direction, the plurality of first interconnection regions including a first edge interconnection region closest to the first edge, the first edge interconnection region not having a second interconnection region between the first edge interconnection region and the first edge, the plurality of second interconnection regions including a second edge interconnection region adjacent to the first edge interconnection region; A first doped layer disposed in a first region and a second doped layer disposed in a second region; A plurality of first fine gates and a plurality of second fine gates, wherein the first fine gates are disposed in the first region and electrically connected to the first doped layer, and the second fine gates are disposed in the second region and electrically connected to the second doped layer; the first fine gates are discontinuous in the first series region and continuous in the second series region, and the second fine gates are discontinuous in the second series region and continuous in the first series region. A first edge gate line, the first edge gate line being closer to the first edge than the first edge connecting region, the first edge gate line being electrically connected to at least a portion of the first fine gate; and A first busbar is disposed in at least one of the first regions, the first busbar is connected to the first edge grid line and the first fine grid and extends from the first edge grid line to the second edge concatenation region, the first busbar includes a first portion located in the first edge concatenation region and a second portion located on the first fine grid, the first portion does not have the first fine grid below it, and the height of the first portion is less than the height of the second portion.

[0005] In some embodiments, the thickness of the first portion is less than the thickness of the second portion.

[0006] In some embodiments, the width of the first portion is greater than the width of the second portion, and the cross-sectional area of ​​the first portion is the same as that of the second portion.

[0007] In some embodiments, the difference between the height of the first portion and the height of the second portion is 6μm-8μm.

[0008] In some embodiments, the back contact battery further includes a back passivation film layer disposed on the back side, the back passivation film layer covering the first region and the second region; The first fine gate at least partially penetrates the back passivation film and is electrically connected to the first doped layer, the second fine gate at least partially penetrates the back passivation film and is electrically connected to the second doped layer, and the first busbar does not penetrate the back passivation film.

[0009] In some embodiments, the first fine gate has a first welding segment in the second serial connection region, and the second fine gate has a second welding segment in the first serial connection region; The height of the first part is lower than the height of the second welding segment, and the difference between the height of the first part and the height of the second welding segment is 5μm-10μm.

[0010] In some embodiments, the width of the first portion is greater than or equal to the width of the first welded segment.

[0011] In some embodiments, the first fine gate has a first welded section within the second edge connection region, and the width of the first busbar is greater than the width of the portion of the first fine gate excluding the first welded section.

[0012] In some embodiments, one end of the first busbar is connected to the first edge gate line, and the other end of the first busbar is connected to the first welded segment in the second edge serialization area.

[0013] In some embodiments, a plurality of second serialization areas include a third edge serialization area closest to the second edge, wherein there is no first serialization area between the third edge serialization area and the second edge, and a plurality of first serialization areas include a fourth edge serialization area adjacent to the third edge serialization area. The back contact battery also includes: A second edge gate line, which is closer to the second edge than the third edge concatenation region, is electrically connected to at least a portion of the second fine gate; and A second busbar is disposed in at least one of the second regions, the second busbar is connected to the second edge grid line and the second fine grid and extends from the second edge grid line to the fourth edge concatenation region, the second busbar includes a third portion located in the third edge concatenation region and a fourth portion located on the second fine grid, the third portion does not have the first fine grid below it, and the height of the third portion is less than the height of the fourth portion.

[0014] In some embodiments, the thickness of the third portion is less than the thickness of the fourth portion.

[0015] In some embodiments, the width of the third portion is greater than the width of the fourth portion, and the cross-sectional area of ​​the third portion is the same as that of the fourth portion.

[0016] In some embodiments, the height difference between the third portion and the fourth portion is 6μm-8μm.

[0017] In some embodiments, the back contact battery further includes a back passivation film layer disposed on the back side, the back passivation film layer covering the first region and the second region; The first fine gate at least partially penetrates the back passivation film and is electrically connected to the first doped layer, the second fine gate at least partially penetrates the back passivation film and is electrically connected to the second doped layer, and the second bus does not penetrate the back passivation film.

[0018] In some embodiments, the first fine gate has a first welding segment in the second serial connection region, and the second fine gate has a second welding segment in the first serial connection region; The height of the third part is lower than the height of the first welding segment, and the difference between the height of the third part and the height of the first welding segment is 7μm-12μm.

[0019] In some embodiments, the width of the third portion is greater than or equal to the width of the second welded segment.

[0020] In some embodiments, the second fine gate has a second welded section within the fourth edge serialization region, and the width of the second bus line is greater than the width of the portion of the second fine gate excluding the second welded section.

[0021] In some embodiments, one end of the second busbar is connected to the second edge grid line, and the other end of the second busbar is connected to the second welding segment.

[0022] This application also provides a battery assembly, which includes a plurality of back contact batteries as described in any of the above claims and a first insulating layer, wherein the first insulating layer is located within the first edge series connection area and disposed on the first portion.

[0023] This application also provides a photovoltaic system, which includes the aforementioned battery components.

[0024] In the back-contact battery, battery module, and photovoltaic system of this application embodiment, the first fine grid is discontinuous at the first series connection region and continuous at the second series connection region. The second fine grid is discontinuous at the second series connection region and continuous at the first series connection region. At least one first region is provided with a first bus line, which is connected to the first edge grid line and the first fine grid and extends from the first edge grid line to the second edge series connection region. The first bus line includes a first portion located within the first edge series connection region and a second portion located on the first fine grid, wherein the first portion does not have the first fine grid below it, and the height of the first portion is less than the height of the second portion. Thus, on the one hand, due to the configuration of the first busbar, even if the first fine grid is disconnected at the first edge series connection area, the current collected by the first edge grid lines can still be transmitted to the solder ribbon located in the adjacent second series connection area through the first busbar, thereby effectively avoiding efficiency loss. On the other hand, since the first fine grid is disconnected at the first edge series connection area, the height of the first part of the first busbar is less than the height of the second part. In the module, after the first insulating layer is set, the height of the first insulating layer can be reduced, thereby reducing the risk of cold solder joints caused by the first insulating layer and reducing the impact of cold solder joints on the back contact cells. In other words, since the first fine grid is disconnected at the first edge series connection area, the height of the first part is lower, thereby reducing the height of the first insulating layer in the module and achieving the purpose of reducing the risk of cold solder joints.

[0025] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a photovoltaic system module provided in an embodiment of this application; Figure 2 This is a schematic diagram of a battery assembly provided in an embodiment of this application; Figure 3 This is a schematic diagram of the planar structure of the back contact battery provided in an embodiment of this application; Figure 4 yes Figure 3 A magnified schematic diagram of the back contact battery at point IV; Figure 5 yes Figure 4 A magnified schematic diagram of the back contact battery at point V; Figure 6 yes Figure 5 A schematic diagram of the cross-sectional structure along line VI-VI of the back contact battery in the diagram. Figure 7 yes Figure 5 A schematic diagram of the cross-sectional structure of the back contact battery along line VII-VII. Figure 8 yes Figure 5 A schematic diagram of the cross-sectional structure of the back contact battery along line VIII-VIII. Figure 9 yes Figure 3 A magnified view of the back contact battery at point IX; Figure 10 yes Figure 9 A magnified view of the back contact battery at point X; Figure 11 yes Figure 10 A schematic diagram of the cross-sectional structure of the back contact battery along line XI-XI. Figure 12 yes Figure 10 A schematic diagram of the cross-sectional structure of the back contact battery along line XII-XII. Figure 13 yes Figure 10 A schematic diagram of the cross-sectional structure of the back contact battery along line XIII-XIII. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. Examples of embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. It should be noted that the embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.

[0028] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "lateral", "longitudinal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "several" means two or more, unless otherwise explicitly specified.

[0030] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0031] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0032] Please see Figure 1 and Figure 2 The photovoltaic system 1000 in this application embodiment may include the battery module 200 in this application embodiment, and the battery module 200 in this application embodiment may include a plurality of back contact batteries 100 in this application embodiment.

[0033] In embodiments of this application, multiple back-contact batteries 100 in the battery assembly 200 can be connected in series to form multiple battery strings. Each battery string can be connected in series, in parallel, or in a series-parallel combination to achieve current collection and output. For example, the connection between individual battery cells can be achieved by welding solder strips, or the connection between individual battery strings can be achieved by busbars. In some embodiments, the individual battery strings can form a battery cell array, and then be packaged together by a front plate, a front adhesive film, a rear adhesive film, and a back plate to form the battery assembly 200.

[0034] In the embodiments of this application, the back contact battery 100 may be a gridless back contact battery; please refer to [link to relevant documentation]. Figures 3-8 The back contact battery 100 in this application embodiment may include a silicon substrate 10, a plurality of first fine gates 20, a plurality of second fine gates 30, a first edge gate line 40 and a first bus line 210.

[0035] Please combine Figures 3-7The silicon substrate 10 has a front side 11 and a back side 12. The back side 12 of the silicon substrate 10 has a first edge 121 and a second edge 122 opposite to each other in a first direction. The back side 12 includes a plurality of first regions 1201 and second regions 1202 alternately arranged along a second direction. A plurality of first doped layers 102 and a plurality of second doped layers 103 are disposed on the back side 11 of the silicon substrate 10. The first doped layers 102 are disposed on the first regions 1201, and the second doped layers 103 are disposed on the second regions 1202. That is, the plurality of first doped layers 102 and the plurality of second doped layers 103 are alternately arranged along the second direction.

[0036] In addition, such as Figure 3 As shown, the back surface 12 has a plurality of first series connection areas 13 and a plurality of second series connection areas 14. The first series connection areas 13 and the second series connection areas 14 are respectively used to provide positive electrode solder strips and negative electrode solder strips, that is, one of the first series connection areas 13 and the second series connection area 14 is a positive electrode series connection area, and the other is a negative electrode series connection area. The second direction intersects the first direction. In some embodiments, the first direction and the second direction can be the longitudinal direction and the transverse direction of the back contact battery 100, respectively, and they are perpendicular to each other. For example, in Figure 3 In the example shown, the first direction is the lateral direction of the back contact battery 100, and the second direction is the longitudinal direction of the back contact battery 100. Of course, in other embodiments, the first and second directions may be other directions, and there is no specific limitation here.

[0037] like Figure 3 and Figure 4 As shown, in a first direction, first connecting areas 13 and second connecting areas 14 are arranged alternately. A plurality of first connecting areas 13 include a first edge connecting area 131 closest to the first edge 121, and there is no second connecting area 14 between the first edge connecting area 131 and the first edge 121. A plurality of second connecting areas 14 may include a second edge connecting area 141 closest to the first edge 121, and the second edge connecting area 141 is adjacent to the first edge connecting area 131. That is to say, a plurality of second connecting areas 14 may include a second edge connecting area 141 adjacent to the first edge connecting area 131.

[0038] That is to say, such as Figure 3 and Figure 4 As shown, in the first connection area 13 and the second connection area 14, the connection area closest to the first edge 121 is the first connection area 13, and the first connection area 13 is referred to as the first edge connection area 131. There are no other connection areas between the first edge connection area 131 and the first edge 121. The second connection area 14 adjacent to the first edge connection area 131 is the second edge connection area 141.

[0039] Please see Figure 6 and Figure 8 In some embodiments, the back contact battery 100 may further include a back passivation film layer 104 disposed on the back surface 12. The back passivation film layer 104 covers the first region 1201 and the second region 1202, that is, the back passivation film layer 104 is at least stacked on the first doped layer 102 and the second doped layer 103. In some embodiments, the back passivation film layer 104 may cover the entire back surface 12, that is, the first doped layer 102, the second doped layer 103, and the regions of the back surface 12 where no doped layer is disposed are all stacked with the back passivation film layer 104.

[0040] In some embodiments, a first passivation layer (not shown) may be disposed between the first doped layer 102 and the silicon substrate 10. The first passivation layer may be, for example, a tunneling layer, an intrinsic amorphous silicon layer, or other film layer. A second passivation layer (not shown) may also be disposed between the second doped layer 103 and the silicon substrate 10. The second passivation layer may be, for example, a tunneling layer, an intrinsic amorphous silicon layer, or other film layer.

[0041] like Figures 3-5 As shown, a plurality of first fine gates 20 and a plurality of second fine gates 30 may be alternately arranged on the back surface 12 along the second direction. The first fine gates 20 are disposed on the first region 1201 and electrically connected to the first doped layer 102, and the second fine gates 30 are disposed on the second region 1202 and electrically connected to the second doped layer 103.

[0042] In some embodiments, in the back contact battery 100, the first fine gate 20 may correspond one-to-one with the first doped layer 102, and the second fine gate 30 may correspond one-to-one with the second doped layer 103. One of the first doped layer 102 and the second doped layer 103 may be a P-type doped layer, and the other may be an N-type doped layer. That is, the first fine gate 20 is located above the first doped layer 102 and corresponds one-to-one with the first doped layer 102, and the second fine gate 30 is located above the second doped layer 103 and corresponds one-to-one with the second doped layer 103. In some embodiments, the first fine gate 20 may completely penetrate the back passivation film 104 to form a complete contact with the first doped layer 102, or it may only partially penetrate the back passivation film 104 to form a localized metallized contact with the first doped layer 102; the specific details are not limited here. Similarly, the second fine gate 30 may completely penetrate the back passivation film 104 to form a complete contact with the second doped layer 103, or it may only partially penetrate the back passivation film 104 to form a localized metallized contact with the second doped layer 103; the specific details are not limited here.

[0043] In the embodiments of this application, all first fine gates 20 and all second fine gates 30 may be intersected with the first serial connection area 13 and the second serial connection area 14. That is, the first serial connection area 13 and the second serial connection area 14 both extend along the second direction to intersect with the first fine gate 20 and the second fine gate 30.

[0044] In some embodiments, the first fine gate 20 may include a first welding segment 201 located within the second serial connection area 14, that is, the first fine gate 20 is continuous in each second serial connection area 14 and has a first welding segment 201 for welding with solder strip in the second serial connection area 14.

[0045] The second fine gate 30 includes a second welding segment 301 located within the first serial connection area 13 (including the first edge serial connection area 131), that is, the second fine gate 30 is continuous in each first serial connection area 13 and has a second welding segment 301 for welding with solder strip at the first serial connection area 13.

[0046] Please see Figures 3-5 The first fine gate 20 is interrupted at the first serial connection area 13 (including the first edge serial connection area 131) and continuous at the second serial connection area 14 (including the second edge serial connection area 142). The second fine gate 30 is interrupted at the second serial connection area 14 (including the second edge serial connection area 141) and continuous at the first serial connection area 13 (including the first edge serial connection area 131).

[0047] In the battery assembly 200, the solder strip in the first series connection area 13 (including the first edge series connection area 131) is used to connect with the second fine grid 30 to realize the current output of the second fine grid 30, and the solder strip in the second series connection area 14 is used to weld to the first fine grid 20 to realize the current output of the first fine grid 20.

[0048] like Figure 3 As shown, the first edge gate line 40 is closer to the first edge 121 than the first edge serial region 131, and the first edge gate line 40 is electrically connected to at least a portion of the first fine gate 20.

[0049] At least one first region 1201 is provided with a first bus line 210, which is connected to the first edge gate line 40 and the first fine gate 20 and extends from the first edge gate line 40 to the second edge connection region 141. Specifically, as Figure 5 As shown, the first busbar 210 can be disposed above the first fine gate 20 and extends continuously from the first edge gate line 40 to the second edge connection area 141 and connects with the first welding segment 201. That is, one end of the first busbar 210 can be connected to the first edge gate line 40, and the other end can be connected to the first welding segment 201 in the second edge connection area 141. Thus, it can be seen that the first busbar 210 is continuous at the first edge connection area 131.

[0050] Specifically, to avoid microcracks in the battery caused by welding at the edge of the first edge 121, the first edge grid line 40 is not used for welding. Instead, it is used to collect the current in the portion of the first fine grid 20 located between the first edge series region 131 and the first edge 121. This current is then collected through the first bus line 210 onto the same polarity solder strip in the second series region 14 (i.e., the second edge series region 141) adjacent to the first edge series region 131. This collects the current in the grid line segment of the first fine grid 20 located at the edge of the first edge 121, improving the efficiency of the back contact battery 100. If the first edge grid line 40 and the first bus line 210 are not provided, the portion of the first fine grid 20 located between the first edge series region 131 and the first edge 121 will form an isolated grid line segment, making it impossible to collect the current in that portion.

[0051] Please combine Figures 5-8 The first busbar 210 includes a first portion 211 located within the first edge connection area 131 and a second portion 212 located on the first fine gate 20. The first portion 211 does not have the first fine gate 20 below it, and the height of the first portion 211 is less than the height of the second portion 212. That is, in the first busbar 210, the first portion 211 is disposed on and connected to the first fine gate 20, while the second portion 212 is located in the first edge connection area 131, and the first fine gate 20 does not have the second portion 212 below it. "The height of the first portion 211 is less than the height of the second portion 212" means that the height of the first portion 211 in the thickness direction is lower than the height of the second portion 212 in the thickness direction.

[0052] like Figure 3 and Figure 4 As shown, in the battery assembly 200, in order to avoid short circuit between the solder strip on the first edge connection area 131 and the first bus line 210, a first insulating layer 50 may be provided on the first part 211 of the first bus line 210. In some embodiments, the first insulating layer 50 may be formed by dispensing or printing, etc., and no specific limitation is made here.

[0053] In the back contact battery 100, battery module 200, and photovoltaic system 1000 of the embodiments of this application, the first fine grid 20 is discontinuous at the first series connection region 13 and continuous at the second series connection region 14. The second fine grid 30 is discontinuous at the second series connection region 14 and continuous at the first series connection region 13 (including the first edge series connection region 131). At least one first region 1201 is provided with a first bus line 210, which is connected to the first edge grid line 40 and the first fine grid 20 and extends from the first edge grid line 40 to the second edge series connection region 141. The first bus line 210 includes a first portion 211 located within the first edge series connection region 131 and a second portion 212 located on the first fine grid 20. The first portion 211 does not have the first fine grid 20 below it, and the height of the first portion 211 is less than the height of the second portion 212. Thus, on the one hand, due to the arrangement of the first busbar 210, even if the first fine grid 20 is disconnected at the first edge series connection area 131, the current collected by the first edge grid line 40 can still be transmitted through the first busbar 210 to the solder ribbon disposed in the adjacent second series connection area 14 (i.e., the second edge series connection area 141), thereby effectively avoiding efficiency loss. On the other hand, since the first fine grid 20 is disconnected at the first edge series connection area 131, the height of the first part 211 of the first busbar 210 is less than the height of the second part 212. In the module, after the first insulating layer 50 is provided, the height of the first insulating layer 50 can be reduced, thereby reducing the risk of cold solder joints caused by the first insulating layer 50 and reducing the impact of cold solder joints on the back contact battery 100. In other words, since the first fine grid 20 is disconnected at the first edge series connection area 131, the height of the first part 211 is lower, thereby the height of the first insulating layer 50 in the module is lower, thus achieving the purpose of reducing the risk of cold solder joints.

[0054] For example, in some possible embodiments, the thickness of the first fine gate 20 may be 5μm-7μm. Since the first fine gate 20 is discontinuous at the first edge serialization region 131, compared to the first fine gate 20 being continuous at the first edge serialization region 131, the height of the first portion 211 of the first bus line 210 located in the first edge serialization region 131 can be reduced by at least 5μm-7μm. This allows the height of the first insulating layer 50 after it is set to be reduced by 5μm-7μm, thereby reducing the risk of poor soldering caused by the first insulating layer 50.

[0055] Please see Figure 6In some embodiments, the first bus 210 does not penetrate the back passivation film layer 104. That is, the first bus 210 is located on the back passivation film layer 104 but does not penetrate it. It can be entirely located on the back passivation film layer 104, or it can be partially embedded in the back passivation film layer 104 but not penetrating it. In this way, direct contact between the first bus 210 and the silicon substrate 10 can be avoided, which would lead to defects in the bulk region and an increase in recombination, effectively improving efficiency. The first bus 210 can be made using a non-burn-through paste.

[0056] As shown above, it is easy to understand that in this application, the first edge gate line 40 is not used for welding; it is only used for current transmission and busing, while the first bus line 210 functions as a transmission line. Figure 3 and Figure 4 It can be seen that, in Figure 3 and Figure 4 In the example shown, if the first edge gate line 40 and the first bus line 210 are not provided, the first fine gate 20 is disconnected at the first edge series region 131. The current of the part of the gate line segment in the first fine gate 20 located between the first edge series region 131 and the first edge 121 cannot be collected. Therefore, by providing the first edge gate line 40 and the first bus line 210, the current of at least part of the isolated gate line segment of the first fine gate 20 located in the edge region can be connected and transmitted to the solder strip provided in the adjacent second series region 14, thereby effectively avoiding efficiency loss.

[0057] Meanwhile, to prevent the solder strips on the first edge serial connection area 131 from contacting the first bus 210 and causing a short circuit, a first insulating layer 50 (e.g., insulating adhesive) needs to be provided at the position corresponding to the first bus 210 and the first edge serial connection area 131. In this case, if the first fine grid 20 below the first bus 210 is continuous in the first edge serial connection area 131, then after placing the first insulating layer 50, the height of the first insulating layer 50 is higher than the height of the second welding segment 301 of the second fine grid 30. In this case, the solder strips in the first edge serial connection area 131 will short-circuit during welding. During the connection process, it is easy for poor soldering to occur with the second fine grid 30, resulting in the current on part of the second fine grid 30 not being effectively collected (especially the second fine grid 30 adjacent to the first bus line 210, which is most likely to have poor soldering). Based on this, in this application, the first fine grid 20 is not below the first part 211 of the first bus line 210, which can reduce the height of the first part 211, thereby reducing the height of the first insulating layer 50 after the first insulating layer 50 is set, thereby reducing the risk of poor soldering, improving the reliability of the welding, and ensuring the performance of the back contact battery 100.

[0058] Furthermore, in some embodiments, the number of first bus lines 210 may be multiple, and the multiple first bus lines 210 may be arranged at intervals along the second direction.

[0059] like Figures 3-5 As shown, in this case, as described above, the first fine gate 20 includes a first welding segment 201 corresponding to the second serial connection area 14. That is, the first fine gate 20 has a first welding segment 201 in the second serial connection area 14. Specifically, the first fine gate 20 may be continuous at each second serial connection area 14 and have a first welding segment 201 for welding with solder strip at each second serial connection area 14.

[0060] The second fine gate 30 includes a second welding segment 301 corresponding to the first serial connection area 13. That is, the second fine gate 30 has a second welding segment 301 in the first serial connection area 13. Specifically, the second fine gate 30 is continuous in each first serial connection area 13 and has a second welding segment 301 for welding with solder strip in the first serial connection area 13.

[0061] In some embodiments, in the first fine gate 20, the width (i.e., the length in the second direction) of the first welding segment 201 may be greater than the width of the remaining portion. This increases the contact area between the first fine gate 20 and the solder strip, improving welding stability. In some embodiments, in the second fine gate 30, the width (i.e., the length in the second direction) of the second welding segment 301 may be greater than the width of the remaining portion.

[0062] In some embodiments, the width of the first bus 210 is greater than the width of the portion of the first fine gate 20 excluding the first welded section 201. Thus, by setting the width of the first bus 210 to be wider, bus transmission loss can be reduced and efficiency improved.

[0063] In some embodiments, the thickness of the first portion 211 is less than the thickness of the second portion 212.

[0064] By making the thickness of the first part 211 thinner, the height of the first part 211 can be further reduced, thereby further reducing the height of the first insulating layer 50, and further reducing the risk of poor soldering caused by the first insulating layer 50.

[0065] In some embodiments, the thickness of the second portion 212 can be 3μm-5μm, such as 3μm, 3.5μm, 4μm, 4.5μm, 5μm, or other values ​​between 3μm and 5μm. The thickness of the first portion 211 is 1μm-2μm smaller than the thickness of the second portion 212, such as 1μm, 1.2μm, 1.4μm, 1.6μm, 1.8μm, 2μm, or other values ​​between 1μm and 2μm. This avoids the first portion 211 being too thin, resulting in insufficient impact resistance and a tendency to break.

[0066] For example, in some embodiments, the thickness of the second portion 212 may be 3 μm and the thickness of the first portion 211 may be 2 μm; in other embodiments, the thickness of the second portion 212 may be 4 μm and the thickness of the first portion 211 may be 2 μm-3 μm; and in yet another embodiment, the thickness of the second portion 212 may be 5 μm and the thickness of the first portion 211 may be 3 μm-4 μm.

[0067] Furthermore, in such an embodiment, the width of the first portion 211 is greater than the width of the second portion 212, where the width refers to the dimension in the second direction. In this case, the cross-sectional area of ​​the first portion 211 is equal to the cross-sectional area of ​​the second portion 212.

[0068] This configuration can reduce the thickness of the first part 211 while avoiding excessive transmission resistance of the first part 211, which would cause transmission loss. In other words, this configuration can reduce the thickness of the first part 211 while making the transmission resistance of the first part 211 and the second part 212 basically the same, thereby avoiding increased transmission loss.

[0069] In some embodiments, the difference between the height of the first portion 211 and the height of the second portion 212 is 6μm-8μm, that is, in the thickness direction, the height of the first portion 211 is 6μm-8μm lower than the height of the second portion 212, for example, 6μm, 6.2μm, 6.4μm, 6.6μm, 6.8μm, 7μm, 7.2μm, 7.4μm, 7.6μm, 7.8μm, 8μm or other values ​​of 6μm-8μm.

[0070] Thus, when setting the first insulating layer 50, the height of the first insulating layer 50 can be reduced by 6μm-8μm, thereby reducing the impact of poor soldering caused by the first insulating layer 50.

[0071] In some embodiments, the width of the first portion 211 may be greater than the width of the first welding segment 201. Thus, by setting the width of the first portion 211 to be wider, the height of the first portion 211 can be reduced as much as possible within the same cross-sectional area, thereby minimizing the risk of incomplete soldering. Of course, in some embodiments, the width of the first portion 211 may also be the same as the width of the first welding segment 201; that is, in this application, the width of the first portion 211 may be greater than or equal to the width of the first welding segment 201. In some embodiments, the height of the first portion 211 is lower than the height of the second welding segment 301, and the difference between the height of the first portion 211 and the height of the second welding segment 301 is 5μm-10μm, such as 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 9μm, 9.5μm, 10μm or other values ​​between 5μm and 10μm.

[0072] With this configuration, during the component welding process, after the first insulating layer 50 is set, the height of the first insulating layer 50 and the height of the second welding segment 301 will not differ too much, thereby reducing the impact of poor soldering caused by the first insulating layer 50.

[0073] In some embodiments, after the first insulating layer 50 is provided, the height of the first insulating layer 50 may be flush with the height of the second welding segment 301, or the height of the first insulating layer 50 may be less than the height of the second welding segment 301. In this way, the effect of poor soldering caused by the first insulating layer 50 can be almost completely eliminated.

[0074] In some possible embodiments, after the first insulating layer 50 is provided, the height of the first insulating layer 50 may also be greater than the height of the second welding segment, and the height difference between the two is less than or equal to 15μm, such as 1μm, 2μm, 3μm, 4μm, 5μm, 9μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm or other values ​​less than 15μm.

[0075] In this way, by controlling the height difference between the first insulating layer 50 and the second welding section 301 within this reasonable range, the impact of poor soldering caused by the first insulating layer 50 can be effectively reduced.

[0076] In some embodiments, when the height of the first insulating layer 50 is greater than the height of the second welding segment 301, the height difference between the first insulating layer 50 and the second welding segment 301 is preferably less than 8 μm, for example, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 9 μm, 7 μm, or 8 μm. Specifically, through repeated research and verification by the inventors of this application, it has been found that by preferably setting the height difference between the two within the preferred range of less than 8 μm, the risk of poor soldering caused by the first insulating layer 50 can be essentially completely eliminated.

[0077] Please see Figures 3-5In some embodiments, the back contact battery 100 may further include a first auxiliary connection line 60, which may be disposed within the first edge serial connection area 131. In the second direction, at least one side of the first busbar 210 is provided with the first auxiliary connection line 60, and the first auxiliary connection line 60 connects at least two second fine grids 30 located on the same side of the first busbar 210. For example, Figures 3-5 As shown, in some embodiments, at least two second fine gates 30 preferably connected to the first auxiliary connection line 60 include second fine gates 30 adjacent to the first bus line 210 (i.e., Figure 3 and Figure 4 In some embodiments, the first auxiliary connection line 60 is preferably connected to the second fine gate 30 closest to the first bus line 210, and the first auxiliary connection line 60 is also connected to at least one of the remaining second fine gates 30 located on the same side as the second fine gate 30. That is, the first auxiliary connection line 60 is preferably connected to at least one of the second fine gates 30 adjacent to the first bus line 210 and at least one of the remaining second fine gates 30 on the same side.

[0078] Thus, by setting the first auxiliary connection line 60, the risk of poor soldering caused by the first insulating layer 50 can be further reduced. Even if poor soldering occurs between the second fine grid 30 and the solder strip near the first insulating layer 50 due to the setting of the first insulating layer 50, the presence of the first auxiliary connection line 60 allows the poorly soldered second fine grid 30 to still achieve current convergence output through the first auxiliary connection line 60, reducing the impact of poor soldering and thus ensuring the efficiency of the back contact battery 100.

[0079] like Figure 3 and Figure 4 As shown in the embodiments of this application, in order to minimize the impact of poor soldering, when the first bus line 210 has a second fine gate 30 on both sides, it is preferable to simultaneously provide a first auxiliary connection line 60 on both sides of the first bus line 210.

[0080] In some embodiments, the width (i.e., the length in the second direction) of the first bus 210 may be greater than the width (i.e., the length in the second direction) of the portion of the first fine gate 20 located outside the second serial area 14 (i.e., the portion of the first fine gate 20 excluding the first solder section 201). That is, the width of the first bus 210 is greater than the width of the portion of the first fine gate 20 excluding the first bus 210 and the first solder section 201.

[0081] Therefore, since the first busbar 210 needs to perform the function of busbar transmission, setting the width of the first busbar 210 wider can reduce transmission losses during the busbar process and improve efficiency. Furthermore, simply setting the width of the first busbar 210 wider can reduce the amount of slurry used while reducing busbar transmission losses, thereby reducing costs.

[0082] Specifically, such as Figure 3 and Figure 4 As shown in the embodiments of this application, in the first bus line 210, it is continuous only at the first edge connection area 131, and broken at the other first connection areas 13. Meanwhile, the first bus line 210 is continuous at the second connection area 14 and has a first welded section 201 at the second connection area 14. Only the first bus line 210 performs the busing function. Therefore, in some embodiments, to save slurry and reduce costs, only this portion of the grid line segment can be made wider.

[0083] Furthermore, in some embodiments, the width (length in the second direction) of the first bus 210 may be greater than or equal to the width of the first weld segment 201. Herein, the width of the first weld segment 201 refers to its length in the second direction. This ensures that no significant transmission loss occurs during the merging process.

[0084] Please see Figure 3 and Figure 4 In some embodiments, the first edge gate line 40 is electrically connected to all the first fine gates 20.

[0085] In this way, the current collected by the isolated grid segments in all the first fine grids 20 located between the first edge series region 131 and the first edge 121 can be combined, thereby maximizing the efficiency of the back contact battery 100.

[0086] Of course, in some embodiments, the first edge gate line 40 may only be electrically connected to a portion of the first fine gates 20. In such cases, the number of first fine gates 20 not electrically connected to the first edge gate line 40 is less than or equal to four. Thus, even if some of the first fine gates 20 are not connected to the first edge gate line 40, their number is very small and will not cause excessive efficiency loss or product defects.

[0087] In some embodiments, the first auxiliary connection line 60 connects 2-20 second fine gates 30. By setting the number of second fine gates 30 connected to the first auxiliary connection line 60 within this reasonable range, the impact of poor soldering can be minimized or even eliminated.

[0088] In embodiments of this application, the number of first bus lines 210 may be a single line. In such cases, the first auxiliary connecting line 60 may be provided only on one side of the first bus line 210, or the first auxiliary connecting line 60 may be provided on both sides of the first bus line 210; no specific limitation is imposed here. When the first bus line 210 has a second fine gate 30 on both sides, it is preferable to provide the first auxiliary connecting line 60 on both sides.

[0089] Furthermore, it should be noted that in this application, when there are multiple first bus lines 210, the first auxiliary connecting line 60 can be provided only on one or both sides of some of the first bus lines 210, while the first auxiliary connecting line 60 can be omitted on both sides of the remaining first bus lines 210. In this case, the problem of cold solder joints in some locations can still be solved. In this application, it is preferable that the first auxiliary connecting line 60 is provided on both sides of each first bus line 210. Of course, if the first bus line 210 is located at the third edge 123, then the first auxiliary connecting line 60 only needs to be provided on one side of the first bus line 210.

[0090] Of course, please see Figure 3 and Figure 4 In some embodiments, the number of first bus lines 210 can also be multiple. Setting multiple first bus lines 210 can shorten the current confluence path, effectively reduce the confluence transmission loss, and improve efficiency.

[0091] In this case, a first auxiliary connecting line 60 is provided between each of the two adjacent first bus lines 210, and the first auxiliary connecting line 60 located between the two adjacent first bus lines 210 connects all the second fine grids 30 located between the two adjacent first bus lines 210.

[0092] In this way, by connecting the first auxiliary connection line 60 to all the second fine grids 30 between two adjacent first bus lines 210, the influence of poor soldering can be basically completely eliminated, and the efficiency of the back contact battery 100 can be improved as much as possible.

[0093] Specifically, in such an embodiment, the number of first busbars 210 in the back contact battery 100 can be selected according to the actual situation such as the size of the battery cell and the loss during the transmission process, and is not limited here.

[0094] Please see Figures 3-5 In some embodiments, the back contact battery 100 further includes a second auxiliary connection line 90, which is disposed within the second edge serial connection area 141. In the second direction, the second auxiliary connection line 90 connects the first bus line 210 and at least one first fine grid 20 located on one side of the first bus line 210.

[0095] Thus, by setting a second auxiliary connection line 90 in the second edge series connection area 141, the phenomenon that the current transmitted from the first bus line 210 cannot be collected can be effectively avoided by the solder strip in the second edge series connection area 141 having poor soldering or poor contact at the first bus line 210.

[0096] Specifically, such as Figure 4 and Figure 7 As shown, in such an embodiment, the number of second auxiliary connecting lines 90 can be the same as the number of first bus lines 210, and the two correspond one-to-one. When the first bus line 210 is in the middle position (i.e., the first bus line 210 has first fine gates 20 on both sides), the second auxiliary connecting line 90 connects to the first bus line 210, and also connects to the two first fine gates 20 adjacent to the first bus line 210 (i.e., the first fine gates 20 located on both sides of the first bus line 210 and adjacent to it).

[0097] The silicon substrate 10 has a third edge 123 and a fourth edge 124 in a second direction. When the gate line closest to the third edge 123 is a first fine gate 20 and a first bus line 210 is provided on the fine gate, the first bus line 210 has the first fine gate 20 on only one side. In this case, a second auxiliary connection line 90 connected to the first bus line 210 located at the third edge 123 connects at least the first fine gate 20 adjacent to the first bus line 210. The number of first fine gates 20 connected by the second auxiliary connection line 90 is 1-6. For example, in Figure 3 and Figure 4 In this context, the second auxiliary connecting line 90 connects the six first fine grids 20 closest to the third edge 123, and the specific connection is not limited here.

[0098] Similarly, when the grid line closest to the fourth edge 124 is a first fine grid 20 and a first bus line 210 is provided on this fine grid, the first bus line 210 has a first fine grid 20 on only one side. In this case, the second auxiliary connecting line 90 connected to the first bus line 210 located at the fourth edge 124 connects at least the first fine grid 20 adjacent to the first bus line 210, and the number of first fine grids 20 connected by the second auxiliary connecting line 90 is 1-6. For example, in Figure 3 and Figure 4 In this context, the second auxiliary connecting line 90 connects the six first fine grids 20 closest to the fourth edge 124, but the specific connection is not limited here.

[0099] In some embodiments, the distance between the first edge concatenation area 131 and the first edge 121 is greater than or equal to 2 mm and less than or equal to 20 mm.

[0100] This avoids the situation where the distance between the first edge serial connection area 131 and the first edge 121 is too small, causing the welding position to be too close to the first edge 121 and resulting in microcracks in the back contact battery 100, thus reducing the risk of microcracks. It also avoids the situation where the distance between the first edge serial connection area 131 and the first edge 121 is too large, resulting in excessively long isolated grid line segments between the first edge serial connection area 131 and the first edge 121, leading to excessive losses during the transmission path.

[0101] Specifically, in such an embodiment, the distance between the first edge connecting area 131 and the first edge 121 can be, for example, any value between 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm or 2mm-20mm, and is not limited here.

[0102] Please see Figure 3 as well as Figures 9-13 In some embodiments, a plurality of second concatenation areas 14 include a third edge concatenation area 142 closest to the second edge 122, wherein there is no first concatenation area 13 between the third edge concatenation area 142 and the second edge 122, that is, as Figure 3 and Figure 10 As shown, in the first concatenation area 13 and the second concatenation area 14, the concatenation area closest to the second edge 122 is the second concatenation area 14, and this second concatenation area 14 is designated as the third edge concatenation area 142. There are no other concatenation areas between the third edge concatenation area 142 and the second edge 122. A plurality of first concatenation areas 13 include a fourth edge concatenation area 132 adjacent to the third edge concatenation area 142.

[0103] The back contact battery 100 may further include a second edge grid line 110 and a second bus line 310. The second edge grid line 110 is closer to the second edge 122 than the third edge series region 142, and the second edge grid line 110 is electrically connected to at least a portion of the second fine grid 30. At least one second region 1202 contains the second bus line 310, which is connected to the second edge grid line 110 and the second fine grid 30 and extends from the second edge grid line 110 to the fourth edge series region 132. Specifically, as... Figure 9 and Figure 10 As shown, the second busbar 310 can be disposed above the second fine gate 30 and extends continuously from the second edge gate line 110 to the fourth edge connection area 132 and connects with the second welding section 301. That is, one end of the second busbar 310 can be connected to the second edge gate line 110, and the other end can be connected to the second welding section 301 in the fourth edge connection area 132. Thus, it can be seen that the second busbar 310 is continuous at the third edge connection area 142.

[0104] Specifically, to avoid microcracks in the battery caused by welding at the edge of the second edge 122, the second edge grid line 110 is not used for welding. Instead, it is used to collect the current in the portion of the second fine grid 30 located between the third edge series region 142 and the second edge 122. The current is then collected through the second bus line 310 onto the same polarity solder strip in the first series region 13 (i.e., the fourth edge series region 132) adjacent to the third edge series region 142. This collects the current in the grid line segment of the second fine grid 20 located at the edge of the second edge 122, improving the efficiency of the back contact battery 100. If the second edge grid line 110 and the second bus line 310 are not provided, the portion of the second fine grid 30 located between the third edge series region 142 and the second edge 122 will form an isolated grid line segment, resulting in the inability to collect the current in that portion.

[0105] Please combine Figures 5-8 The second busbar 310 includes a third portion 311 located within the third edge connection area 142 and a fourth portion 312 located on the second fine gate 30. The second fine gate 30 is not located below the third portion 311, and the height of the third portion 311 is less than the height of the fourth portion 312. That is, in the second busbar 310, the third portion 311 is disposed on and connected to the second fine gate 30, while the fourth portion 312 is located in the third edge connection area 142, and the second fine gate 20 is not located below the fourth portion 312. "The height of the third portion 311 is less than the height of the fourth portion 312" means that the height of the third portion 311 in the thickness direction is lower than the height of the fourth portion 312 in the thickness direction.

[0106] like Figure 3 and Figure 9 As shown, in the battery assembly 200, in order to avoid short circuit between the solder strip on the third edge series connection area 142 and the second bus 310, a second insulating layer 120 may be provided on the second bus 310. In some embodiments, the second insulating layer 120 may be formed by dispensing or printing, etc., and there is no specific limitation here.

[0107] Thus, on the one hand, due to the arrangement of the second bus 310, even if the second fine grid 30 is disconnected at the third edge series connection area 142, the current collected by the second edge grid line 110 can still be transmitted through the second bus 310 to the solder ribbon disposed in the adjacent fourth edge series connection area 132, thereby effectively avoiding efficiency loss. On the other hand, since the second fine grid 30 is disconnected at the third edge series connection area 142, the height of the third part 311 of the second bus 310 is less than the height of the fourth part 312. In the module, after the second insulating layer 120 is provided, the height of the second insulating layer 120 can be reduced, thereby reducing the risk of cold solder joints caused by the second insulating layer 120 and reducing the impact of cold solder joints on the back contact cell 100. In other words, since the second fine grid 30 is disconnected at the third edge series connection area 142, the height of the third part 311 is lower, thereby the height of the second insulating layer 120 in the module is lower, thus achieving the purpose of reducing the risk of cold solder joints.

[0108] For example, in some possible embodiments, the thickness of the second fine gate 30 may be 5μm-7μm. Since the second fine gate 30 is discontinuous at the third edge concatenation region 142, compared to the second fine gate 20 being continuous at the third edge concatenation region 142, the height of the third portion 311 of the second bus line 310 in the third edge concatenation region 142 can be reduced by at least 5μm-7μm. This allows the height of the second insulating layer 120 after its installation to be reduced by 5μm-7μm, thereby reducing the risk of poor soldering caused by the second insulating layer 120.

[0109] Please see Figure 11 In some embodiments, the second bus 310 does not penetrate the back passivation film 104. That is, the second bus 310 is located on the back passivation film 104 but does not penetrate it. It can be entirely located on the back passivation film 104, or it can be partially embedded in the back passivation film 104 but not penetrating it. This avoids direct contact between the second bus 310 and the silicon substrate 10, preventing defects in the bulk region and increased recombination, thus effectively improving efficiency. The second bus 310 can be made using a non-burn-through paste.

[0110] Specifically, as shown above, it is easy to understand that in this application, the second edge grid line 110 is not used for welding; it is only used for current transmission and busing, and the function of the second bus line 310 is to collect and transmit current. Figure 3 and Figure 10 It can be seen that, in Figure 3 and Figure 9In the example shown, if the second edge gate line 110 and the second bus line 310 are not provided, the second fine gate 30 is disconnected at the third edge series region 142. The current of the portion of the gate line segment in the second fine gate 30 located between the third edge series region 142 and the second edge 122 cannot be collected. Therefore, by providing the second edge gate line 110 and the second bus line 310, the current of at least a portion of the isolated gate line segment of the second fine gate 30 located in the edge region can be connected and transmitted to the solder strip provided in the adjacent second series region 14, thereby effectively avoiding efficiency loss.

[0111] Meanwhile, to prevent the solder strips on the third edge serial connection area 142 from contacting the second bus 310 and causing a short circuit, a second insulating layer 120 (e.g., insulating adhesive) needs to be provided at the position corresponding to the second bus 310 and the third edge serial connection area 142. However, in this case, if the second fine grid below the second bus 310 is continuous at the third edge serial connection area, then after placing the second insulating layer 120, the height of the second insulating layer 120 is higher than the height of the first welding segment 201 of the first fine grid 20. In this case, the solder strips in the third edge serial connection area 142 will short-circuit during welding. During the connection process, it is easy for poor soldering to occur with the first fine grid 20, resulting in the current on part of the first fine grid 20 not being effectively collected (especially the first fine grid 30 adjacent to the second bus line 310, which is most likely to have poor soldering). Based on this, in this application, the second fine grid 30 is not located below the third part 311 of the second bus line 310, which can reduce the height of the third part 311, thereby reducing the height of the second insulating layer 120 after it is set, thus reducing the risk of poor soldering, thereby improving the reliability of the welding and ensuring the performance of the back contact battery 100.

[0112] Furthermore, in some embodiments, there may be multiple second bus lines 310, which may be arranged at intervals along a second direction. In some embodiments, the width of the second bus line 310 is greater than the width of the portion of the second fine gate 30 excluding the second welding section 301. Thus, by setting the width of the second bus line 310 to be wider, the bus transmission loss can be reduced and the efficiency improved.

[0113] In some embodiments, the thickness of the third portion 311 is less than the thickness of the fourth portion 312.

[0114] By making the thickness of the third part 311 thinner, the height of the third part 311 can be further reduced, thereby further reducing the height of the second insulating layer 120, and further reducing the risk of poor soldering caused by the second insulating layer 120.

[0115] In some embodiments, the thickness of the fourth portion 312 can be 3μm-5μm, such as 3μm, 3.5μm, 4μm, 4.5μm, 5μm, or other values ​​between 3μm and 5μm. The thickness of the third portion 311 is 1μm-2μm smaller than the thickness of the fourth portion 312, such as 1μm, 1.2μm, 1.4μm, 1.6μm, 1.8μm, 2μm, or other values ​​between 1μm and 2μm. This avoids the third portion 311 being too thin, resulting in insufficient impact resistance and a tendency to break.

[0116] For example, in some embodiments, the thickness of the fourth portion 312 may be 3 μm and the thickness of the third portion 311 may be 2 μm; in other embodiments, the thickness of the fourth portion 312 may be 4 μm and the thickness of the third portion 311 may be 2 μm-3 μm; and in yet another embodiment, the thickness of the fourth portion 312 may be 5 μm and the thickness of the third portion 311 may be 3 μm-4 μm.

[0117] Furthermore, in such an embodiment, the width of the third portion 311 is greater than the width of the fourth portion 312, where the width refers to the dimension in the second direction. In this case, the cross-sectional area of ​​the third portion 311 is equal to the cross-sectional area of ​​the fourth portion 312.

[0118] This configuration can reduce the thickness of the third part 311 while avoiding excessive transmission resistance and transmission loss caused by the third part 311. In other words, this configuration can reduce the thickness of the third part 311 while making the transmission resistance of the third part 311 and the fourth part 312 basically the same, thereby avoiding increased transmission loss.

[0119] In some embodiments, the difference between the height of the third portion 311 and the height of the fourth portion 312 is 6μm-8μm, that is, in the thickness direction, the height of the third portion 311 is 6μm-8μm lower than the height of the fourth portion 312, for example, 6μm, 6.2μm, 6.4μm, 6.6μm, 6.8μm, 7μm, 7.2μm, 7.4μm, 7.6μm, 7.8μm, 8μm or other values ​​of 6μm-8μm.

[0120] Thus, when setting the second insulating layer 120, the height of the second insulating layer 120 can be reduced by 6μm-8μm, thereby reducing the impact of poor soldering caused by the second insulating layer 120.

[0121] In some embodiments, the width of the third portion 311 may be greater than the width of the second welding segment 301. Thus, by setting the width of the third portion 311 to be wider, the height of the third portion 311 can be reduced as much as possible within the same cross-sectional area, thereby minimizing the risk of incomplete soldering. Of course, in some embodiments, the width of the third portion 311 may also be the same as the width of the second welding segment 301; that is, in this application, the width of the third portion 311 may be greater than or equal to the width of the second welding segment 301. In some embodiments, the height of the third portion 311 is lower than the height of the first welding segment 201, and the difference between the height of the third portion 311 and the height of the second welding segment 201 is 7μm-12μm, such as 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 10.5μm, 11μm, 11.5μm, 12μm or other values ​​between 7μm and 12μm.

[0122] With this configuration, during the component welding process, after the second insulating layer 120 is installed, the height of the second insulating layer 120 and the height of the first welding segment 201 will not differ too much, thereby reducing the impact of the second insulating layer 120 on the poor soldering.

[0123] Specifically, in such an embodiment, in the back contact battery 100, the height of the first region 1201 is 2μm-3μm higher than the height of the second region 1202. After setting the first busbar 210 and the second busbar 310, when the thickness of the first part 211 of the first busbar 210 and the third part 311 of the second busbar 310 is the same, the height difference between the first part 211 and the second welding section 301 is smaller than the height difference between the third part 311 and the first welding section 201.

[0124] In some embodiments, after the second insulating layer 120 is provided, the height of the second insulating layer 120 may be flush with the height of the first welding segment 201 or the height of the second insulating layer 120 may be less than the height of the first welding segment 201. In this way, the effect of poor soldering caused by the second insulating layer 120 can be basically completely eliminated.

[0125] In some possible embodiments, after the second insulating layer 120 is provided, the height of the second insulating layer 120 may also be greater than the height of the first welding segment 201, and the height difference between the two is less than or equal to 15μm, such as 1μm, 2μm, 3μm, 4μm, 5μm, 9μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm or other values ​​less than 15μm.

[0126] Thus, by controlling the height difference between the second insulating layer 120 and the first welding section 201 within this reasonable range, the impact of poor soldering caused by the second insulating layer 120 can be effectively reduced.

[0127] In some embodiments, when the height of the second insulating layer 120 is greater than the height of the first solder segment 201, the height difference between the second insulating layer 120 and the first solder segment 201 is preferably less than 8 μm, for example, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 9 μm, 7 μm, or 8 μm. Specifically, through repeated research and verification by the inventors of this application, it has been found that by preferably setting the height difference between the two within the preferred range of less than 8 μm, the risk of poor soldering caused by the second insulating layer 120 can be essentially eliminated.

[0128] Please see Figure 3 as well as Figures 9-10 In some embodiments, the back contact battery 100 may further include a third auxiliary connection line 130 disposed within the third edge serial connection area 142. In the second direction, at least one side of the second busbar 310 is provided with the third auxiliary connection line 130, and the third auxiliary connection line 130 connects at least two first fine grids 20 located on the same side of the second busbar 310. In some embodiments, preferably, the at least two first fine grids 20 connected to the third auxiliary connection line 130 include the first fine grid 20 adjacent to the second busbar 310 (i.e.,...). Figure 3 and Figure 9 The first fine gate 20 closest to the second busbar 310. That is, in some embodiments, the third auxiliary connection line 130 is preferably connected to the first fine gate 20 closest to the second busbar 310, and the third auxiliary connection line 130 is also connected to at least one of the remaining first fine gates 20 located on the same side as the second fine gate 30. That is, the third auxiliary connection line 130 is preferably connected to at least one of the first fine gates 20 adjacent to the second busbar 310 and at least one of the remaining first fine gates 20 on the same side.

[0129] Thus, by setting the third auxiliary connection line 130, the risk of poor soldering caused by the second insulating layer 120 can be further reduced. Even if poor soldering occurs between the first fine grid 20 and the solder strip near the second insulating layer 120 due to the setting of the second insulating layer 120, the presence of the third auxiliary connection line 130 allows the poorly soldered first fine grid 20 to achieve current convergence output through the third auxiliary connection line 130, reducing the impact of poor soldering and thus ensuring the efficiency of the back contact battery 100.

[0130] Please see Figure 3 and Figure 9In some embodiments, the back contact battery 100 is a gridless back contact battery. Among a plurality of second fine grids 30, the second fine grids 30 are interrupted at the second series connection area 14 and continuous at the first series connection area 13. The second bus line 310 is continuous at the third edge series connection area 142 and interrupted at the remaining second series connection areas 14, and continuous at the first series connection area 13.

[0131] like Figure 3 and Figure 9 As shown in the embodiments of this application, in order to minimize the impact of poor soldering, when the second bus line 310 has a first fine gate 20 on both sides, it is preferable to simultaneously provide a third auxiliary connection line 130 on both sides of the second bus line 310.

[0132] In some embodiments, the width (i.e., the length in the second direction) of the second bus 310 may be greater than the width (i.e., the length in the second direction) of the portion of the second fine gate 30 located outside the first serial area 13 (i.e., the portion of the second fine gate 30 excluding the second weld segment 301). That is, the width of the second bus 310 is greater than the width of the portion of the second fine gate 30 excluding the second bus 310 and the second weld segment 301.

[0133] Therefore, since the second busbar 310 needs to perform the function of busbar transmission, setting the width of the second busbar 310 wider can reduce transmission losses during the busbar process and improve efficiency. Furthermore, simply setting the width of the second busbar 310 wider can reduce the amount of slurry used while reducing transmission losses, thereby lowering costs.

[0134] Specifically, such as Figure 3 and Figure 9 As shown in the embodiments of this application, in the second bus 310, it is continuous only at the third edge connection area 142, and broken at the other second connection areas 14. Meanwhile, the second bus 310 is continuous at the first connection area 13 and has a second welded section 301 at the first connection area 13. Only the second bus 310 performs the busing function. Therefore, in some embodiments, to save slurry and reduce costs, only this portion of the grid line segment can be made wider.

[0135] Furthermore, in some embodiments, the width (length in the second direction) of the second bus 310 may be greater than or equal to the width of the second weld segment 301. Herein, the width of the second weld segment 301 refers to its length in the second direction. This ensures that no significant transmission loss occurs during the merging process.

[0136] Please see Figure 3 and Figure 9In some embodiments, the second edge gate line 110 is electrically connected to all the second fine gates 30. In this way, the current collected by the isolated gate line segments located between the third edge series region 142 and the second edge 122 in all the second fine gates 30 can be combined to maximize the efficiency of the back contact battery 100.

[0137] Of course, in some embodiments, the second edge gate line 110 may also be electrically connected to some of the second fine gates 30. In such cases, the number of second fine gates 30 not electrically connected to the second edge gate line 110 is less than or equal to four. Thus, even if some of the second fine gates 30 are not connected to the second edge gate line 110, their number is very small and will not cause excessive efficiency loss or product defects.

[0138] In some embodiments, the third auxiliary connection line 130 connects 2 to 20 first fine gates 20. Thus, by setting the number of first fine gates 20 connected to the third auxiliary connection line 130 within this reasonable range, the impact of poor soldering can be minimized or even eliminated.

[0139] In embodiments of this application, the number of second bus lines 310 may be a single line. In such cases, the third auxiliary connecting line 130 may be provided only on one side of the second bus line 310, or the third auxiliary connecting line 130 may be provided on both sides of the second bus line 310; the specific provision is not limited here. When the second bus line 310 has a first fine gate 20 on both sides, it is preferable to provide the third auxiliary connecting line 130 on both sides.

[0140] Furthermore, it should be noted that in this application, when there are multiple second bus lines 310, the third auxiliary connecting line 130 may be provided only on one or both sides of some of the second bus lines 310, while the third auxiliary connecting line 130 may not be provided on both sides of the remaining second bus lines 310. In this case, the problem of cold solder joints in some locations can still be solved. In this application, it is preferable that the third auxiliary connecting line 130 is provided on both sides of each second bus line 310.

[0141] Of course, please see Figure 3 and Figure 9 In some embodiments, the number of second bus lines 310 can also be multiple. Setting multiple second bus lines 310 can shorten the current bus path, effectively reduce bus transmission loss, and improve efficiency.

[0142] In this case, a third auxiliary connection line 130 is provided between each of the two adjacent second bus lines 310, and the third auxiliary connection line 130 located between the two adjacent second bus lines 310 connects all the first fine grids 20 located between the two adjacent second bus lines 310.

[0143] In this way, by connecting the third auxiliary connection line 130 to all the first grids 20 between two adjacent second bus lines 310, the influence of poor soldering can be basically completely eliminated, and the efficiency of the back contact battery 100 can be improved as much as possible.

[0144] Of course, in some alternative embodiments, the third auxiliary connection line 130 may be provided only on one side of the second bus line 310, and there is no specific limitation here.

[0145] Specifically, in such an embodiment, the number of second busbars 310 in the back contact battery 100 can be selected according to the actual situation such as the size of the battery cell and the loss during the transmission process, and is not limited here.

[0146] Please see Figure 3 as well as Figure 9 and Figure 10 In some embodiments, the back contact battery 100 may further include a fourth auxiliary connection line 160, which is disposed in the fourth edge serial connection area 132. In the second direction, the fourth auxiliary connection line 160 connects the second bus line 310 and at least one second fine grid 30 located on one side of the second bus line 310.

[0147] Thus, by setting the fourth auxiliary connection line 160 in the fourth edge series connection area 132, the phenomenon that the current transmitted from the second bus line 310 cannot be collected can be effectively avoided by the solder strip in the fourth edge series connection area 132 having poor soldering or contact at the second bus line 310.

[0148] Specifically, such as Figure 9 As shown, in such an embodiment, the number of fourth auxiliary connecting lines 160 can be the same as the number of second bus lines 310, and the two correspond one-to-one. When the second bus line 310 is in the middle position (i.e., the second bus line 310 has second fine gates 30 on both sides), the fourth auxiliary connecting line connects the second bus line 310 and connects the two second fine gates 30 adjacent to the second bus line 310 (i.e., the second fine gates 30 located on both sides of the second bus line 310 and adjacent to it).

[0149] In some embodiments, the width (length in the first direction) of the fourth auxiliary connection line 160 is greater than the width (length in the second direction) of the portion of the second fine gate 30 located outside the first serial connection area 13 (i.e., the portion of the second fine gate 30 excluding the second solder section 301). Thus, since the fourth auxiliary connection line 160 serves to transmit and combine current when a poor solder joint occurs at the second bus line 310, setting the width of the fourth auxiliary connection line 160 wider can also reduce transmission losses during the current combining process and improve efficiency.

[0150] In some embodiments, the distance between the third edge concatenation area 142 and the second edge 122 is greater than or equal to 2 mm and less than or equal to 20 mm.

[0151] This avoids the situation where the distance between the third edge series connection area 142 and the second edge 122 is too small, causing the welding position to be too close to the second edge 122 and resulting in microcracks in the back contact battery 100, thus reducing the risk of microcracks. It also avoids the situation where the distance between the third edge series connection area 142 and the second edge 122 is too large, resulting in excessively long isolated grid line segments between the third edge series connection area 142 and the second edge 122, leading to excessive losses during the transmission path.

[0152] Specifically, in such an embodiment, the distance between the third edge connecting area 142 and the second edge 122 can be, for example, any value between 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm or 2mm-20mm, and is not limited here.

[0153] In the above embodiments, the polarity of the third edge series connection area 142 is opposite to that of the first edge series connection area 131, and the structures of the two edges of the back contact battery 100 in the first direction are different and asymmetrical. It is understood that in some possible embodiments, the polarity of the third edge series connection area 142 and the first edge series connection area 131 may also be the same. In this case, the structures of the two edges of the back contact battery 100 in the first direction are the same and symmetrical. That is to say, in this case, in the back contact battery 100, the two series connection areas closest to the second edge 122 are symmetrical to the first edge series connection area 131 and the second edge series connection area 141. A bus line, auxiliary connection line and other structures are also provided on one side of the second edge 122, which are completely stacked with one side of the first edge 121. To avoid being verbose, the specific structure will not be described in detail here.

[0154] In the description of this specification, the references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0155] Furthermore, the above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A back-contact battery, characterized in that, include: A silicon substrate having opposing front and back sides, the back side having opposing first and second edges in a first direction, the back side including a plurality of first regions and a plurality of second regions alternately arranged along a second direction intersecting the first direction, the back side having a plurality of first interconnection regions and a plurality of second interconnection regions, the first interconnection regions and the second interconnection regions being alternately arranged in the first direction, the plurality of first interconnection regions including a first edge interconnection region closest to the first edge, the first edge interconnection region not having a second interconnection region between the first edge interconnection region and the first edge, the plurality of second interconnection regions including a second edge interconnection region adjacent to the first edge interconnection region; A first doped layer disposed in a first region and a second doped layer disposed in a second region; A plurality of first fine gates and a plurality of second fine gates, wherein the first fine gates are disposed in the first region and electrically connected to the first doped layer, and the second fine gates are disposed in the second region and electrically connected to the second doped layer; the first fine gates are discontinuous in the first series region and continuous in the second series region, and the second fine gates are discontinuous in the second series region and continuous in the first series region. A first edge gate line, which is closer to the first edge than the first edge connecting region, and is electrically connected to at least a portion of the first fine gate; and A first busbar is disposed in at least one of the first regions, the first busbar is connected to the first edge grid line and the first fine grid and extends from the first edge grid line to the second edge concatenation region, the first busbar includes a first portion located in the first edge concatenation region and a second portion located on the first fine grid, the first portion does not have the first fine grid below it, and the height of the first portion is less than the height of the second portion.

2. The back contact battery according to claim 1, characterized in that, The thickness of the first part is less than the thickness of the second part.

3. The back contact battery according to claim 2, characterized in that, The width of the first part is greater than the width of the second part, and the cross-sectional area of ​​the first part is the same as that of the second part.

4. The back contact battery according to claim 1, characterized in that, The height difference between the first part and the second part is 6μm-8μm.

5. The back contact battery according to claim 1, characterized in that, The back contact battery also includes a back passivation film layer disposed on the back side, the back passivation film layer covering the first region and the second region; The first fine gate at least partially penetrates the back passivation film and is electrically connected to the first doped layer, the second fine gate at least partially penetrates the back passivation film and is electrically connected to the second doped layer, and the first busbar does not penetrate the back passivation film.

6. The back contact battery according to claim 1, characterized in that, The first fine gate has a first welding section within the second serial connection area, and the second fine gate has a second welding section within the first serial connection area; The height of the first part is lower than the height of the second welding segment, and the difference between the height of the first part and the height of the second welding segment is 5μm-10μm.

7. The back contact battery according to claim 6, characterized in that, The width of the first portion is greater than or equal to the width of the first welded segment.

8. The back contact battery according to claim 1, characterized in that, The first fine gate has a first welded section within the second edge connection area, and the width of the first busbar is greater than the width of the portion of the first fine gate excluding the first welded section.

9. The back contact battery according to claim 8, characterized in that, One end of the first busbar is connected to the first edge grid line, and the other end of the first busbar is connected to the first welding segment in the second edge serial connection area.

10. The back contact battery according to claim 1, characterized in that, The plurality of second serialization areas include a third edge serialization area closest to the second edge, wherein there is no first serialization area between the third edge serialization area and the second edge, and the plurality of first serialization areas include a fourth edge serialization area adjacent to the third edge serialization area; The back contact battery also includes: A second edge gate line, which is closer to the second edge than the third edge concatenation region, is electrically connected to at least a portion of the second fine gate; and A second busbar is disposed in at least one of the second regions, the second busbar is connected to the second edge grid line and the second fine grid and extends from the second edge grid line to the fourth edge concatenation region, the second busbar includes a third portion located in the third edge concatenation region and a fourth portion located on the second fine grid, the third portion does not have the first fine grid below it, and the height of the third portion is less than the height of the fourth portion.

11. The back contact battery according to claim 10, characterized in that, The thickness of the third part is less than the thickness of the fourth part.

12. The back contact battery according to claim 11, characterized in that, The width of the third part is greater than the width of the fourth part, and the cross-sectional area of ​​the third part is the same as that of the fourth part.

13. The back contact battery according to claim 10, characterized in that, The height difference between the third part and the fourth part is 6μm-8μm.

14. The back contact battery according to claim 10, characterized in that, The back contact battery also includes a back passivation film layer disposed on the back side, the back passivation film layer covering the first region and the second region; The first fine gate at least partially penetrates the back passivation film and is electrically connected to the first doped layer, the second fine gate at least partially penetrates the back passivation film and is electrically connected to the second doped layer, and the second bus does not penetrate the back passivation film.

15. The back contact battery according to claim 11, characterized in that, The first fine gate has a first welding section within the second serial connection area, and the second fine gate has a second welding section within the first serial connection area; The height of the third part is lower than the height of the first welding segment, and the difference between the height of the third part and the height of the first welding segment is 7μm-12μm.

16. The back contact battery according to claim 15, characterized in that, The width of the third part is greater than or equal to the width of the second welded segment.

17. The back contact battery according to claim 10, characterized in that, The second fine gate has a second welded section within the fourth edge connection area, and the width of the second busbar is greater than the width of the portion of the second fine gate excluding the second welded section.

18. The back contact battery according to claim 17, characterized in that, One end of the second busbar is connected to the second edge grid line, and the other end of the second busbar is connected to the second welding section.

19. A battery assembly, characterized in that, include: The back contact battery according to any one of claims 1-18; and A first insulating layer is located within the first edge serialization area and disposed on the first portion.

20. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 19.

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